Apparatus for roasting material



Nov. 3, 1931. c. J. SCHIFFERLE 3 3 I APPARATUS FOR ROASTING MATERIAL Filed March 27, 1929 INVENTOR Char-IesJc'lzfr/e ATTORNEY Patented Nov'. 3, 1931 NET/;BD s

.QAT EFICE- CEARLES J. SCHIFFEBLE, OF OAKLAND, CALIFQRNIA, ASSIGNOR TO EARRY E.

` STRUTHEES, OF BERKELEY, CALIWRNA APPARATUS FOR EOASTING MATEEML A lication' filed March 27, me. Serial ne. 3503512;

t'urnace to conserve heat and to control the reaction in the urnace.

Another object of my invention is the provision, in an apparatus otthe character described, of means effecting the dischargeot substances given ofi from the material, at a comparatively low temperature to prevent coales'cing and sintering of the sulostances, which would otherwise occur at higher temperatures.

Another object of the invention is the proto the furnace:

A still further object of the invention s the provsion of improved means for {passin material into the tui-hace and of improve means for discharging material therefrom.

M invention possesses other, objects and valuable features, some of which will loe set for-th in the following description of my in vntion which is illustrated in the drawings torming part of the specification. It is to be understood that I do not limit myself to the showing made by the said description and drawngs, as l: may adopt varying forms of my invention within the scope of the claimso Referring to the drawings: e Figure l is a more-or less diagrammatic longitudinal sectional view of the .apparatus, portions being shown in elevation to disclose W the Construction clearly. i ?figure 2 is a 'transverse sectional View taken in a plane indicated by line 2-2 of Figure 1. I

Figure 3 is a transverse sectional view, partly in elevation, looking in the same direction vision of improved means tor supplying air' '.terial such as iron or steel.

gears mesh with goairs of spaced opinions 6,

gournaled in as lFigure 2, and illustrating a modified form of teedingmeans which may -be employed ,with the furnace. In terms of broad inlusion, the apparatus comprses a furnace in which the material '50 is roasted; and preferahly the furnace is provided adjacent one end with an expansion and cooling chamber for substances :tormed during combustion of material. Fines, open- I ing from the furnace at difierent portions thereof, are provided. Preferably one of the flues opens from the exp ansion chamher,-- while. another of the flues opens from the opposite end of the furnace, dampersheing ositioned in the fiuesfor controlling the fi w of substances :from the furnaceand the reaction therein. 'lt is preterred 'to have the fiues in communication, so that the vaporized sulostancesmay leave throu h a single exit. Means are provided torpassng material into the furnace, and means are also provided for discharging residue therefrom. Preferably the side of the turnace is prhvided with an air duet for permitting intermittent flow of air into the furnace.

'i have chosen, as a pr' t'erred emhodiment ot' my invention, an app ratus which-is used tor the production of Zinc oxide from materials such as zine ore, Zinc sulphide or Zinc carbonate, although I am aware that the apparatus may he used for roasting many other metal 'compounds, such as those containing Copper or cadmiun. Also, the apparatus may be used for the roasting of non-metallic materials, such as 'for the production of'sulphur dioxide from sulphur or sulphur ores.

En greater detail, the apparatus comprises a roasting" furnace, which is preferably cylindrical to form a drum 2, made of suitable ma- The drum is rotatably mounted by means of annular gears 3, surrounding the drum and fixed thereto by suitable means such as hrackets 4; and the suitable hearings beneath the stationary hoods 11 and 12, which are held by suitable supports 13 and 14 respectively. Stationary hood 11 is at the discharge end of the furnace; and adj acent this end of the furnace and spaced inwardly therefrom is a circular apertured plate 16 forming an eXpansion chamber 17, which is preferabl'y unlined. The remaining portion of the furnace provides a combustion chamber 18 which is preferably lined with any suitable refractory material 19, such as fire brick, and forming stepped sections which decrease in cross section toward the feeding end of the furnace, so that material fed therein may work toward the discharge end when the furnace is rotated. It is apparent, however, that a sloping furnace may be employed instead of the latter Construction. y

At the feeding end of the furnace at which hood 12 is located, and passingthrough the hood 12, are provided a burner 20, which may be either an oil or gas burner, and an air line 21 for supplying air to the furnace as desired. The aperture 8 adjacent this end of the furnace is partially closed by a semi-circular plate 22. fiXed to the hood and having an aperture through which material from a screw conveyor 23 may be passed into the furnace. Any suitable means may be employed for driving the conveyor, although ll prefer to drive it from drive shaft 7 by sprockets 24 and chain 26.

Means are provided for controlling the temperatures and reactions in the furnace. A flue 27 opening from the expansion chamber 17 of the furnace and into stationary hood 11, is provided with a damper 28; and a flue 29 opening from the opposite end of the furnace and into stationary hood 12, is provided with a damper 31. Preferably flue 27 is bent at right angles and communicates with flue 29, which in turn may be connected with an exhaust fan 32, from which the substances given oli' during combustion of material may be led to suitable baghouses for separation. A damper 33 is preferab ly placed in the discharge hood 11, also to provide a temperature control( By the use of the described arrangement of fiues and'dampers, delicate control is provide'd, resulting in a fine product and conservation of heat. For example, if the apparatus is used for producing zinc oxide from Zinc carbonate, the zinc carbonate is first finely divided and mixed with crushed coke, and the material is fed into the furnace as described. Combustion is 'initiated by the burner 20, suflicient air being provided through air line 21. At a temperature of between 2200 F. and 2400 F., the followng reactions occur, in which the coke aids n the combuston to form pure Zinc vapor WhlCh oxdzes to Zinc oXide:

:CO 02 2 CO:

If the temperature in the combustion chamber of the furnace is too low and therefore the reaction is incomplete, the dampers may be so adjusted as to hold'the vapors in the furnace a longer period, such as by partially closing damper 28 and opening damper 31. If the temperature is too high, damper 28 may be opened further to provide more draft through the furnace. These conditions may be determined by a skilled operator who observes the character of the fiame. Also, a temperature control is obtained by means of damper 33 in thedischarge hood.

In the expansion chamber, the vapors expand and cool; and preferably the dampers 28 and31 are regulated to maintain a temperature of between 400 and 500 1 of the substances that leave the expansion chamber and passout through fiue 27. In the furnaces heretofore used for roasting Zinc ores, the

.gases leave at a temperature of about 1800 F., at which temperature the ZnO sinters and coalesces into large masses, which is undesirable for a quality product.

It is to be noted that since the temperature of gases leaving the furnace is very low, as Compared with that of prior furnaces, a vast amount of heat is conserved; therefore it is unnecessary to have the burner 20 in continual operation, it being only necessary that it be burningwhen the. tem erature in the combustion chamber falls o Means are provided for intermittently discharging residue and ash from the furnace.

Adjacent the expansion chamber 17, a conduit 34:, lined eXteriorly with refractory material, is positioned. Referring to Figure 2, the conduit is disposed angularly with respect to the radius of the furna ce, so that when it is on the underside thereof it is disposed substantially perpendicular to a line 36 which indicates the relatively constant angle of repose of material in the drum, effected by rotation thereof in the direction of the direction arrow. Material will begin to discharge at this point. Uponmvemet of the conduit approximately 90, it will then be substantially parallel with the surface of the materialin the drum, hence any material remaining in the conduit will slide back onto the material in the drum and at the upper portion thereof, without creating dust particles that might be carried out of the drum with 'products of combustion. The speed of' rotation of the drum for a given'material is practically always the same; and at a constant speed, the material will lie at a substantially constant angle of repose; hence the inclination of the conduit may be readily ascertained. i

When the conduit 34 is on the lower side of the drum, material will fall therethrough.

, When the conduit is on the upper side of the M drum, it is preferred to have it closed to conserve heat; therefore a cover 37 is hinged to the 'turnace adjacent the edge of the outer opening of the conduit, the cover being pror vided with a stop 38, adapted to limit outward movement thereof, so that when the cover is on the under side of the furnace, the conduit is open, and When it is raised upon rotation of the furnace, the cover may `fall V by gravity to close the Conduit.

In addition to the discharge Conduit 34, I -preferably provide a large clean-out port 39 and cover 41 therefor, in order that the turnace may be cleaned when desired.

Air ducts are provided in the furnace, 2@ which is formed with apertures 42 on opposite sides thereof. I Conduits 43, communicating with these apertures, project into the furnace for supplying air theretof These condnits are preferably lined with refrace@ tory material exteriorly thereof, and are provided with covers 4:4 hinged to the :turnace in a manner the same as that described :tor cover' 37 of the discharge conduit 34; so that during part of the furnace rotation, a n aperture tt is open to permit passage of air and during another part of the rotation, the cover automatically closes the aperture.

In Figure 3,- lt have illustrated a modified form of means for passing material into the to turnace, the rest ot the apparatus Construction being the same as that described. A conduit 46, projecting intothe turnace, is disposed angularly with respect to the rad us of thefurnace and, when on the underside of tt the turnace, substantally perpendicular to a line 47 indicating the constant angle of repose of material in the-furnace when it is rotated. The Conduit projects beyond the outer wall of the furnace; and at its outer tend, it is provided with a scoop'48 having sides and a bottomhut open at the top, and hingedly mounted on the Conduit, the scoop being formed with stop 49 for limiting downward movement of the scoop when ,it is on t the underside of the furnace.

Upon rotation of the furnace. the scoop is adapted to gather material from a pile of material beneath the furnace; and upon raising of the scoop by rotation of the furtt nace, the material passes through the conduit and discharges into the furnace and onto the upper portionof material therein, without reation of dust particles as previously explained. When the scoop reaches an upper portion' of 'its novement, will fall by gravity to close the Conduit, the conduithe- ,ing provided with a flange 51, adapted to form a closure for the open top of the scoop when it falls. t

ll claim:

1. An apparatus for roasting material comprsing a furnace provided with an expansion chamber for substances formed during combustion of the material, a flue open'- ing from the eXpansion chamber, a second flue opening from the furnace at another portion thereof, and dampers in said flues. 2. An apparatus for roasting material comprising a furnace provided With an expansion chamber for substances formed during domhustion of the material, a flue opening from the expansion chamber, a second flue opening from the furnace at another portion thereof', one of said flues communicating with the other of said flues, and dampers in said flues.

3. An apparatus' for roasting material' comprising ,a furnace having ends and provided with an eXpansion chamber adjacent one end thereof, means adj acent the other end for passing material into the furnace, means for efiecting movement of the material toward the expansion chamber, a fine opening 'from said expansion chamber, a second tlue opening from the furnace adjacent the other end,uand danpersin said flues.

4. An apparatus for* roasting material 'comprising a furnace .having ends and provided with an eXpansion chamber adjacent one end thereof, means 'adj acent the other end for passing material .into the furnace, means for efi'ecting movement of the material toward the expansion chamber, a fiue opening from' said expansion chamber,a second fiue opening from the turnace adjacent the other end, one of said flues communicating with tfihe other ofsaid flues, and dampers in said ues.

5. An apparatus forroasting material i comprising a rotatably mounted cylindrical furnace having an aperture at each end thereof and provided with an expansion chamher adj acent one end thereof, hoods for said apertures, a flue opening from the furnace and into one of said hoods, a second fiue opening from the 'furnace and into the other ot said hoods, and dampers in said flues.

6. An apparatus for roasting material comprising a rotatably mounted cylindrical furnace having an aperture at each end thereof and provided With an expansqn hamber adjacent one end thereof, hoods for said apertures. aflue opening from the furnace and.

into one of said hoods, a second fineopening` from the furnace and into' the other of said hoods, dampers in said flues, and a damper for the hood adj acent the expansion chamber. 7. An apparatus tor roasting material conprisng a rotatably mounted cylindrical furace, means ior rotatng the furnace, and

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a Conduit leading into the furnace for the passage of material and mounted for rotation therewith, said Conduit being angularly disposed wth respect to the radus of the furnace.

8. An apparatus for roasting material comprising a rotatably mounted c lindrical furnace, means for rotating the urnace, a. Conduit leading into the furnace for the passage of material and mounted for rotation therewth, sad conduit being angularly disposed With respect to the radius of the furnace, and a hinged cover for said conduit.

9. An apparatus for roasting material comprisng a rotatably mounted cylindrcal furnace having an aperture adjacent each end thereof, an expanson chamber and hood adjacent the aperture at one end thereofla hood for the aperture adjacent the other end, a fiue opening from the furnace and into one of said hoods, a second fiue opening from the furnace and into the other of said hoods, and dampers in said flues. i

n testimony whereof, I have hereunto set my hand.

CHARLES J. SCHIFFERLE.

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